1. Field of the Invention
The present invention relates to a rinsing method for performing a rinsing process on a substrate, such as a semiconductor wafer, after a developing process is performed on a light-exposed pattern formed thereon, and a developing method including such a rinsing process.
2. Description of the Related Art
For example, in the process of manufacturing semiconductor devices, a so-called photolithography technique is used. According to this photolithography technique, a resist liquid is applied onto the surface of a semiconductor wafer (which will be referred to as “wafer”) to form a resist film. Then, the resist film is subjected to a light exposure process in accordance with a predetermined pattern. Then, the resist film with the light-exposed pattern thus formed is subjected to a developing process.
In the developing process used as one of the steps of the photolithography technique, a developing solution is supplied onto the wafer to form a developing solution puddle. Then, this state is held for a predetermined time to promote the developing process by natural convection. Thereafter, the developing solution is thrown off, and purified water is then supplied as a cleaning liquid to wash out the developing solution remaining on the wafer. Then, the wafer is rotated at a high speed to throw off the developing solution and cleaning liquid remaining on the wafer, thereby drying the wafer.
In recent years, circuit structures of semiconductor devices are increasingly miniaturized with advances in light exposure techniques and so forth, and thus resist patterns with a smaller size and a higher aspect ratio have come into use. Accordingly, a problem arises such that resist patterns are pulled and bent by a surface tension of a rinsing liquid, i.e., so-called “pattern fall” is caused, when the rinsing liquid is being removed from the gaps between the patterns during a throwing-off/drying operation at the end of the developing step described above.
As a technique to solve this problem, Jpn. Pat. Appln. KOKAI Publication No. 7-142349 discloses a proposed technique such that, for example, a surfactant solution is mixed into a rinsing liquid to decrease the surface tension of the rinsing liquid. Further, Jpn. Pat. Appln. KOKAI Publication No. 2001-5191 discloses a process in which a surfactant is supplied when a rinsing process is performed on a substrate after a developing process.
Unlike the conventional process using purified water, however, where a surfactant is used together with a rinsing liquid, a problem arises such that the surfactant generates particles and contaminates the wafer. In other words, the wafer suffers precipitation defects due to the surfactant, which deteriorate the quality. Further, another problem arises such that the surfactant dissolves resist patterns, and/or the surfactant causes CD (Critical Dimension) fluctuations. However, so far, optimum process conditions in light of these problems have not yet been found to rinsing processes using a surfactant.